Corbicula an annotated bibliography 1774 2005

Large quantities of Corbicula fluminea and Corbicula formosana are collected along the Tansui and Keelung rivers in Taipei. So far as is known, very few people eat them raw. Both of these rivers, particularly the latter, are exposed to dangerous pollution. Thus, the purposes of this investigation were to learn the sanitary quality of these clams and to take precautions against the possible infection of people eating them.

The present study is based on the data of the plate count of the vital bacterial and of the number of coliform bacteria present in the clams. The examination done during the months from June to December showed the highest plate count of 67,000 per 1 ml and the highest coliform MPN (most probable number) of 35 x 10⁵ per 100 ml.

Shimizu, T. and Y. Ohta. 1968. Carotenoids in bivalves: III. Carotenoids in Corbicula shell. Bulletin of the Japanese Society of Scientific Fisheries 34(3):210 213.

The carotenoid component of Corbicula japonica shell was studied. The absorption spectra of the crude oils and unsaponifiable matters of the sample differed markedly with each other. This phenomenon was not encountered in the cases of short neck clams and hard clam. Among six fractionated carotenoids, lutein, lutein ester, and beta carotene were identified, and a taraxanthin like pigment, though it remained unsettled, was found in four samples. The lutein content of C. japonica is 10 to 20 times more than hard clams.

Shimer, H. R. and R. S. Schrock. 1944. Index Fossils of North America. Technology Press, Massachusetts Institute of Technology (Cambridge). 419 pp.

Corbicula durkeei, Corbicula occidentalis, and Corbicula cytheriformis are briefly discussed with regard to their general shell anatomy, and stratigraphic and geographic location in North America.

Shimura, S. 1983. Cercaria corbiculae sp. nov. in a brackish water clam Corbicula japonica Prime from Lake Shinji, Shimane Prefecture, Japan. Fish Pathology 10(2):61 64. [In Japanese with English summary]

A monorchiid cercaria was found in a brackish water clam Corbicula japonica collected from Lake Shinji, Shimane Prefecture, Honshu, Japan, and a new species, Cercaria corbiculae, is proposed. The present species is a distome, pharyngeate cercaria with a slender long tail, no stylet, no eyespots, long ceca, three pairs of penetration gland cells, 16 flame cells, and a saccate excretory vesicle deflected to the left.

Shiomi, K., J. Arita, Y. Nagashima and A. Shinagawa. 1995. Detection of a proteinaceous toxin in the brackishwater clam (Corbicula japonica). Toxicon 33(5):699-702.

Water extracts from the brackishwater clam (Corbicula japonica) were found to be lethal to mice upon i.v. injection. Muscular tissues (foot muscle, adductor muscle, mantle muscle, mantle and siphon) were all toxic while gill and viscera (mid-gut gland, testis and ovary) were nontoxic; the highest toxicity was observed with foot muscle. The toxin was judged to be a thermolabile, basic protein with a molecular weight of about 13,000.

Shively, S. H. and M. F. Vidrine. 1984. Fresh water mollusks in the alimentary tract of a Mississippi map turtle. Biology of Inland Waters 47:27 29.

Shuba, P. J., H. E. Tatem, and J. H. Carroll. 1978. Biological Assessment Methods to Predict the Impact of Open Water Disposal of Dredged Material. U.S. Army Corps of Engineers Waterways Experiment Station (Vicksburg, Mississippi). Report No. WES TR D 78 50. 167 pp. [Also NTIS No. AD A060502/2]

Shuzhi, R. 1983. Monitoring 666 and DDT in J River by using Corbicula fluminea (Müller) as an indicator. Acta Ecologica Sinica 3(4):314. [Chinese]

Sickel, J. B. 1973. A new record of Corbicula manilensis (Philippi) in the southern Atlantic slope region of Georgia. The Nautilus 87(1):11 12.

Based on previous extensive surveys, it appears that Corbicula manilensis, was introduced into the Altamaha River system of Georgia in 1968, initially into the Ocmulgee River from which it has spread downstream into the Altamaha River, being found there for the first time in the summer of 1971. This is a first record of this Asian species occurring in the Southern Atlantic Slope region.

Sickel, J. B. 1976. An Ecological Study of the Asiatic Clam, Corbicula manilensis (Philippi, 1841), in the Altamaha River, Georgia, with Emphasis on Population Dynamics, Productivity and Control Methods. Ph.D. Dissertation, Emory University (Atlanta, Georgia). 140 pp.

Corbicula manilensis (Philippi, 1841) is a recent invader in the Altamaha River. Since its first discovery in small, localized populations in 1971, C. manilensis has become a significant biotic component throughout the coastal plain region of the Altamaha system. It now appears to be one of the most abundant macroinvertebrates in the river and has significantly altered the dynamics of the Altamaha ecosystem. In 1974 larval density reached a recorded maximum of 52,000/m², and the population density of clams greater than 2 mm in length in a typical population over a heterogenous substratum reached 1165/m².

Monthly samples were taken from March 1973 to October 1974, with a modified Petersen grab along two 15 m transects in the Altamaha River approximately 188 km by river from the coast. The length, width, and height of each clam was recorded and a length frequency distribution was plotted from which growth rates were determined. Clams grew to a length of 11 13 mm in their first year and to 21 mm in two years.

Biomass was determined for 66 clams ranging in length from 4.5 to 26 mm and a regression equation was calculated and used to estimate clam biomass from measurements of shell length (y = 0.00550 + x^3.18 where y = tissue dry weight in mg and x = shell length in mm; r = 0.99). The productivity of Corbicula manilensis was calculated and a potential harvestable production was estimated to be 87 kcal/m²/yr.

The net productivity of Corbicula manilensis from April, 1973 to April, 1974, was 75.8 kcal/m²/yr at Transect A and 80.3 kcal/m²/yr at Transect B. The similarity of the two productivities even though the substratum composition was not a limiting factor and that some other factor, probably food availability which was the same at both transects had a greater influence on productivity.

Plankton samples were examined to determine the abundance and seasonal distribution of planktonic larvae. Larvae were present in the water column throughout the year except for the month of March. A peak density of 2377/kl occurred in May representing the major spawning period which began when the water temperature rose above 20^oC.

The larval preference for substrata on which to settle was determined by placing containers of various substrata in the river for a two week period and counting the number of larvae that settled on each substratum. With a water current velocity of 25 35 cm/sec the largest number of larvae settled on fine sand with fewer on coarse sand, fewer still on mud, and none on concrete. The different substrata were arranged in a Latin square design with respect to each other and to the current direction. Neither the orientation of substrata nor current direction affected larval settling on the different substrata.

The impact of Corbicula manilensis on the native clams (Unionidae) was examined. C. manilensis do not appear to be affecting adult native clams directly; however, they may be excluding the juvenile unionids which may result in the loss of many endemic species.

Bioassay experiments were conducted to determine the toxicity of chlorine to larvae of Corbicula manilensis. A six compartment continuous flow apparatus was designed and used to test five concentrations of chlorine and one control simultaneously. It was determined that 0.1 mg/1 of free residual chlorine will provide effective control is applied continuously. Chlorine concentrations of 0.5 mg/1 for 72 hrs or 1.0 mg/1 for 52 hrs are required for 100% mortality of larvae.

Adult Corbicula manilensis were kept in 0.5, 10, 25, 50 and 100% sea water (30 ppt) for 48 hrs, and the freezing point depression, delta F, of their blood was determined with a cryoscope. Clams were not able to osmoregulate in sea water above 10% (3 ppt) which may explain why no C. manilensis were found in brackish water at the mouth of the Altamaha.

The caloric content of freeze dried clam tissue was determined with a Phillipson microbomb calorimeter to be 5.02 cal/mg dry weight and 5.29 cal/mg ash free dry weight. The value 5.02 cal/mg dry weight was used to calculate Corbicula manilensis productivity.

Sickel, J. B. 1976. Population growth and productivity of Corbicula manilensis (Philippi) in the Altamaha River, Georgia (Bivalvia: Corbiculidae). Association of Southeastern Biologists, Bulletin 23(2):96. [Abstract]

Since its first discovery in the Altamaha River in 1971 to the fall of 1974, Corbicula manilensis has increased in numbers from a few individuals to more than 2500/m² in favorable habitats. The average clam grew to a length of 13 mm in the first year and to 21 mm after two years of growth. From April 1973 to October 1974, clam biomass from a 15 m transect and measured as tissue dry weight increased from 2.18 g/m² to 39.1 g/m². Caloric content of clam tissue was 5.02 kcal/g dry weight. Shell length (L) provided a good estimate of tissue dry weight (W) using the regression equation log₁₀W = 3.18(log₁₀L)   2.26 which had a correlation coefficient of 0.99 for 66 clams ranging in length from 4.5 mm to 26 mm.

Sickel, J. B. 1979. Population dynamics of Corbicula in the Altamaha River, Georgia. IN: Proceedings of the First International Corbicula Symposium, J. C. Britton, Ed. Texas Christian University Research Foundation (Ft. Worth), pp. 69 80.

The population dynamics of Corbicula fluminea was studied during its initial invasion of the Altamaha River, Georgia, until a peak population density was reached in October l974. Since that time the fecundity and density have declined establishing what may be a stable population. The invading population appeared to consist of r strategists while the stable population consists of k strategists. Biomass, expressed as tissue dry weight, reached a peak in October 1974 and decreased only 17% by May 1977 while the population density decreased 76%. A power function was used to calculate a regression equation for dry tissue weight and shell length. The Altamaha River population was compared with a population of Corbicula from the Mud River, West Virginia, and individuals in the Mud River populations had significantly greater tissue dry weight relative to shell length than those in the Altamaha.

Sickel, J. B. 1980. Correlation of unionid mussels with bottom sediment composition in the Altamaha River, Georgia. Bulletin of the American Malacological Union 1980: 10 13.

The distribution of the different species of freshwater mussels in the Altamaha River is highly correlated with sediment composition. This study describes the occurrence of eight endemic species prior to the invasion by Corbicula fluminea and recent deterioration of water quality. Changes in sediment composition may endanger some of the mussels.

Sickel, J. B. 1986. Corbicula population mortalities: factors influencing population control. IN: Proceedings of the Second International Corbicula Symposium, J. C. Britton, Ed. American Malacological Bulletin Special Edition No. 2. pp. 89 94.

Several factors potentially affecting population density in Corbicula fluminea are reviewed. These include thermal and oxygen tolerance, silt loads, acidic waters, pollution, bacterial and viral infections, parasites, predators, interspecific competition, genetic changes, and intraspecific competition. All of these factors may influence clam densities and population structure in certain cases. However, it is hypothesized that overpopulation with its attendant strain on energy supplies and stress on individuals is the major cause of the commonly observed mortalities while genetic change through the process of selection may be a major factor in establishing different life history characteristics in different populations.

Sickel, J. B. 1998. Gluttonous feeding behavior in the rhabdocoel, Macrostomum sp., induced by larvae of the Asiatic clam, Corbicula fluminea. Journal of Freshwater Ecology 13(1):135-138.

Larvae of the Asiatic clam, Corbicula fluminea, and their tissue products stimulated gluttonous feeding behavior in a predatory rhabdocoel turbellarian, Macrostomum sp. This gluttony resulted in death of the worms. I suggest that lethal gluttony may be induced by some prey species and serve as an altruistic mechanism sacrificing numerous individuals to eliminate predators and provide greater survival for the remaining prey. This mechanism may be advantageous especially to a species which is expanding its range into regions where it encounters potential predators for the first time. Lethal gluttony could eliminate the predator population before it adapts to the newly introduced prey.

Sickel, J. B. and W. D. Burbanck. 1974. Bottom substratum preference of Corbicula manilensis (Pelecypoda) in the Altamaha River, Georgia. Association of Southeastern Biologists, Bulletin 21(2):84. [Abstract]

Sickel, J. B. and C. C. Chandler. 1982. Commercial Mussel and Asiatic Clam Fishery Evaluation. Kentucky Department of Fish and Wildlife Resources and National Oceanic and Atmospheric Administration, National Marine Fisheries Service, Project No. 2 367 R. Final Report. vii + 77 pp.

When Corbicula fluminea was studied in 1978, large populations were discovered between Cumberland River miles (CRM) 66 70 and were estimated to be a potentially valuable resource for the fishbait industry. A method of harvest was proposed, and this project was designed to monitor the effects of a harvest. Continued examinations of these populations in 1979 and 1980 revealed high summer mortalities with very low recruitment. A harvest was never planed, so that segment of the project designed to monitor the harvest could not be continued.

When sampling was initiated in October 1980, only 10 live Corbicula fluminea were found in 16 grab samples at CRM 67. Many dead shells were found, and the density of live adults had declined from 200/m² in the spring of 1980 to 12/m². Since there was no longer a possibility for a commercial harvest of C. fluminea, this segment of the project was discontinued so that more effort could be directed toward the mussel survey of the lake.

One additional attempt to locate live Corbicula fluminea in Barkley Lake was made on 16 November 1981. Grab samples were examined from CRM 67 to 69. Only dead and often crushed shells were found.

Investigations by SCUBA divers in the lower Tennessee and Cumberland rivers below Kentucky and Barkley dams during l980 and l98l confirmed that Corbicula fluminea was not returning to those rivers after the 1977 die off. Only juveniles were found in sediment samples, and those have failed to mature or survive for over a year.

Sickel, J. B. and M. W. Heyn. 1980. Decline of the Asiatic clam Corbicula fluminea in the Lower Tennessee River and Tennessee River. Bulletin of the American Malacological Union 1980:24 26.

During the years prior to 1977, Corbicula fluminea in the Lower Tennessee River provided a substantial resource to the bait dealers and commercial fishermen using clams as fish bait. In August 1977, there was a massive and unexplained mortality of the clams in the Lower Tennessee and Cumberland Rivers below Kentucky and Berkley Dams. By the end of that summer, bait dealers reported that they could no longer find the clams.

The present study has confirmed the absence of adult, commercially valuable clams in the rivers. Only small, younger than 1 year old clams have been found in benthic samples and fish stomachs from below Kentucky and Barkley Dams to the Ohio River. This represents a significant loss to both fishermen and the natural fish community. Corbicula fluminea less than 1 year old occurred in 68% of the samples from the Cumberland River. Densities in the Tennessee River ranged from 10 to 380/m². Mean monthly shell lengths and clam densities in both rivers indicate that good recruitment occurs in the summer. The populations have started to recover each fall since 1978, but during the following summers the 1 year old clams do not survive. The only reproducing populations of large adult clams were found in Kentucky Lake at mile 61 and in Barkley Lake at miles 66 70.

Sickel, J. B., D. W. Johnson, G. T. Rice, M. W. Heyn and P. K. Wellner. 1981. Asiatic Clam and Commercial Fishery Evaluation. Kentucky Department of Fish and Wildlife, NOAA, National marine Fisheries Service Project No. 2 344 R. vii + 83 pp.

During the 10 years prior to 1977, Corbicula fluminea in the lower Tennessee River provided a substantial resource to the bait dealers and commercial fishermen using clams for fishbait. In August 1977, there was a massive and unexplained mortality of the clams in the lower Tennessee and Cumberland rivers below Kentucky and Barkley Dams. By the end of that summer, bait dealers reported that they could no longer find the clams.

The present study has confirmed the absence of adult, commercially valuable clams in the rivers. Only small, younger than one year old clams have been found in benthic samples and fish stomachs from below Kentucky and Barkley dams to the Ohio River. This represents a significant loss to both the fishermen and the natural fish community. Corbicula fluminea less than one year old occurred in 68% of the samples from the Tennessee River and 36% of samples from the Cumberland River. Densities in the Tennessee River ranged from 10 to 380/m². Mean monthly shell lengths and clam densities in both rivers indicate that good recruitment occurs in the summer. The populations have started to recover each fall since 1978, but during the following summers the one year old clams do not survive. The only reproducing populations of large adult clams were found in Kentucky Lake at mile 61 and in Barkley Lake at miles 66 70.

Dense populations of Corbicula fluminea which would have commercial value as fish bait were found only in Barkley Lake between miles 66 and 70. Present legal methods for harvesting clams limits harvest to shallow waters by a rake with a 20 foot handle. The initial 1978 estimate of the wholesale value of the clams at mile 67 was $250,000. However, high mortalities in the summers of 1979 and 1980 reduced the populations to about 10% of their 1978 densities. No biological causes for the mortalities could be found. Dissolved oxygen was not recorded below 3.6 mg/l, and live mayfly nymphs were present in the clam populations throughout the year. Had low oxygen killed the clams, the nymphs would have been affected also.

A 0.25 m² bottom gram and a dredge were constructed which proved to be efficient methods for harvesting clams in soft sediments from deep water.

Sickel, J. B. and M. B. Lyles. 1981. Chaetogaster limnaei (Oligochaeta: Naididae) inhabiting the mantle cavity of the Asiatic clam, Corbicula fluminea, in Barkley Lake, Kentucky. The Veliger 23(4):361 363.

Samples of the Asiatic clam, Corbicula fluminea, collected from Barkley Lake (Cumberland River), Kentucky, in May and June 1980, contained a symbiotic, naidid oligochaete, Chaetogaster limnaei von Baer, 1827. The worms were found on the gills and mantle within the mantle cavity of 80% of the clams. There was evidence of lesions in the mantle tissues and irregular shell deposition in the clams, but these conditions could not be conclusively related to the presence of Chaetogaster limnaei. Additional studies are being conducted to determine the relationship between Chaetogaster limnaei. Additional studies are being conducted to determine the relationship between Chaetogaster limnaei and Corbicula fluminea.

Sickel, J. B. and S. A. Smallmon. 1978. Thermal and oxygen effects on the heart rate of the Asiatic clam Corbicula manilensis. Association of Southeastern Biologists, Bulletin 25(2):47. [Abstract]

Pin electrodes were placed on either side of the pericardial cavity through small holes drilled in the shell of Corbicula manilensis. The electrodes were cemented to the shell with "Quik Rok", a brand of fast setting Portland cement. The clams were allowed to burrow and assume their natural position under water in Ottawa sand. Heart rate was recorded with a NARCO Bio Systems physiograph using an impedance pneumograph. Temperature and concentrations of dissolved oxygen were altered to determine their effects on the heart rate. The results indicate that this technique can be useful as a biomonitor of environmental conditions and for detecting thermal and oxygen stress in clams.

Sidaroff, S. A. 1929. Les mollusques du lac d'Aral et de ses proches environs. Russkii Hydrobiolocheskii Zhurnal Saratow 8:13 37. [Russian with French summary]

Siegert, L. and W. Weissermel. 1906. Ueber die Gliederung des Diluviums zwischen Halle a. S. und Weissenfels. Zeitschrift der Deutschen Geologischen Gesellschaft 58:32 49.

Siegert, L. and W. Weissermel. 1911. Das Diluviums zwischen Halle a. S. und Weissenfels. Abhandlungen K:oniglich Presse Geologischen Landesanst (Berlin), N.F. Heft 60. 147 pp.

Siegfried, C. A., A. W. Knight and M. E. Kopache. 1978. Ecological Studies in the Western Sacramento San Joaquin Delta During a Dry Year. California State Water Resources Control Board (Sacramento) and the Office of Water Research and Technology (Washington, D.C.). Report No. PAPER 4506. 139 pp. [Also NTIS No. PB 279665/4]

A portion of the Western Sacramento-San Joaquin Delta was studied by the UCD Estuarine Research Group during 1976, a critical dry year. Particularly important to the ecology of the Delta, in 1976, was the low outflow, the fourth-lowest on record. The most important aspect of water quality during 1976 was salinity incursion accompanying low flows. The flow flows caused the entrapment zone to be located upstream from Chipps Island during much of 1976. The location of the entrapment zone in the San Francisco Bay Estuary is thought to be very important in the ecology of the Delta. The benthic community of the Western Delta was dominated by the Asiatic clam (Corbicula manilensis), oligochaetes, the amphipods Corophium stimpsoni and C. spinicorne, and a spionid polychaete, Boccardia ligrerica. These taxa averaged 98% of the total benthic macroinvertebrates collected at each study site. Changes in benthos composition are thought to be related to salinity incursion and changes in substratum composition resulting from the deposition of fine sediments during summer. In general, the upstream channel stations had higher standing crops of benthos than the other stations in the study area in 1976. Total benthic standing crop was lowest near Chipps Island. The standing crop peaked in June and was lowest in November.

Siegfried, C. A., M. E. Kopache and A. W. Knight. 1980. The benthos of a portion of the Sacramento River (San Francisco Bay estuary) during a dry year. Estuaries 3(4):296 307.

Early in 1976 benthic studies were initiated in a 20 km long portion of the Western Sacramento San Joaquin River estuary. Water quality determinations indicated little vertical or horizontal differences in pH, temperature, or dissolved oxygen concentrations within the study area. Low river outflows allowed the encroachment of sea water into the study area, an area normally exposed to fresh or slightly brackish water. The sediment composition changed dramatically at most stations during the year, being dominated by sands early in the year but by silts and clays in late summer. The shift in sediment composition was accompanied by an increase in grease and oil and metals content.

The benthic community of the study area was generally dominated by Corbicula manilensis, Macoma balthica, oligochaetes, the amphipods Corophium stimpsoni and Corophium spinicorne, nematodes, and a spionid polychaete, Boccardia ligerica. These taxa comprised 98% on average of the total benthic macroinvertebrates collected at each study site. The benthic assemblages of each of the stations were generally very similar to one another. Faunal similarities and changes in benthos composition were related to substratum composition and salinity incursion. In general, the upstream   channel stations had higher abundance of benthos than the other stations in the study area. Total benthic abundance was lowest at the downstream end of the study area. Total standing crop peaked in June and was lowest in November. The study indicates that the most important factors controlling the size and species composition of the benthos of the study area was salinity and sediment composition.

Siemers, C. T. 1976. Sedimentology of the Rocktown Channel Sandstone, upper part of the Dakota Formation, Cretaceous, Central Kansas, USA. Journal of Sedimentary Petrology 46:97 123.

Two unidentified species of Corbicula and Corbicula cf. obesa White are reported from the upper Dakota Formation. The species of Corbicula compare somewhat favorably with some of White's species from the brackish to freshwater Laramie Group (Upper Cretaceous to Lower Tertiary) of Utah, New Mexico, Colorado and Montana. Corbicula (Cyrena)? sp. A is similar to Corbicula (Leptesthes) planumbona White referred to as Corbicula downingi (McLearn) by Hattin, and Corbicula (Cyrena)? sp. B may compare with Corbicula occidentalis White or with Corbicula cytheriformis White. In general, these thick walled bivalves can be identified easily as belonging to the family Corbiculidae which is well established as a fresh or brackish water faunal group.

Siluba, M. 1987. Species abundance of Corbicula possoensis, and Melanoides granifera (Mollusca) in Poso Lake, Central Sulawesi. Berita Biologi 3(7):317 320. [Indonesian with English summary]

Corbicula possoensis and Melanoides granifera are the two dominant species of Mollusca occurring in Poso Lake, Indonesia. The high abundance of these two species is distributed among three habitat types: sand, mud sand, and gravel. The abundance of C. possoensis was 126.66/m² in sand, 118.66/m² in mud sand, and 51/m² in gravel.

Silverman, H., E. C. Achberger, J. W. Lynn and T. H. Dietz. 1995. Filtration and utilization of laboratory-cultured bacteria by Dreissena polymorpha, Corbicula fluminea, and Carunculina texasensis. Biological Bulletin 189(3):308-319.

Silverman, H., E. Acberger, S. Medler, J. Lynn and T. Dietz. 1997. Differences between Dreissena polymorpha, Corbicula fluminea, and the unionids in ability to clear bacteria. Seventh International Zebra Mussel and Aquatic Nuisance Species Conference, pg. 30, New Orleans, Louisiana, 28-31January. Louisiana Sea Grant LSU-R-97-018. 1 pp.

Silverman, H., S. J. Nichols, J. S. Cherry, E. Achberger, J. W. Lynn and T. H. Dietz. 1997. Clearance of laboratory-cultured bacteria by freshwater bivalves: Differences between lentic and lotic unionids. Canadian Journal of Zoology/Revue Canadien de Zoologie 75(11):1857-1866.

Nine species of unionids cleared laboratory-raised Escherichia coli from artificial pond water. The six unionid species collected from rivers had higher clearance rates than the three species collected from ponds, when clearance was normalized to millilitres per gram of dry tissue mass per minute. Analysis of variance indicated that all lotic unionids examined form a group with similar clearance rates. When normalized on the basis of gill surface area, rates of clearance by all of the lotic unionids become remarkably similar to one another regardless of mass, but differ significantly from those of the lentic unionids. The cirri found on the laterofrontal cells of the gills of lotic unionids tend to be complex, containing > 25 cilia per cirral plate, while the cirri of the unionid species collected from ponds have smaller cirri (< 16 cilia per cirral plate). There was a strong correlation between cirral surface area (mm super(2)) per milligram of dry tissue and clearance rate among the unionid species studied. As a comparison, Corbicula fluminea and Dreissena polymorpha were also examined and both tended to clear bacteria more rapidly than the lotic unionids.

Simon, O. and A. Boudou. 2001. Simultaneous experimental study of direct and direct plus trophic contamination of the crayfish Astacus astacus by inorganic mercury and methylmercury. Environmental Toxicology and Chemistry 20(6):1206-1215.

An experimental study was carried out to investigate direct and direct plus trophic contamination routes of the crayfish Astacus astacus by inorganic mercury (Hg(II)) or methylmercury (MeHg). Direct exposure was based on low contamination conditions, 300 and 30 ng/L in the dissolved phase, respectively, during 30 d at 20^oC. Trophic exposure was based on daily consumption of the Asiatic clam Corbicula fluminea, previously contaminated during 40 d with similar exposure conditions. The Hg concentrations in the bivalves were very similar: 1,451 ± 287 ng/g for Hg(II) and 1,346 ± 143 ng/g for MeHg. In the crustaceans, Hg bioaccumulation was analyzed at the whole-organism level and in eight organs (gills, stomach, intestine, hepatopancreas, tail muscle, green gland, carapace, and hemolymph), after 15 and 30 d of exposure. Analysis of the results showed marked differences between Hg(II) and MeHg accumulation in favor of MeHg: for the direct route, the ratio between metal concentrations was close to 8; for the trophic route, no significant increase in Hg accumulation was observed for Hg(II) even when the ratio between Hg concentration in the direct plus trophic contamination route and Hg concentration in the direct contamination route was 1.6 for MeHg, with an estimated trophic transfer rate close to 20%. Mercury organotropism was also specifically connected to the exposure conditions, especially at the biological barrier level according to the route of exposure: gills and carapace for the direct route and digestive tract including hepatopancreas for the trophic route.

Simon, O. and A. Boudou. 2002. Utilisation du modele ecrevisse comme espece bioindicatrice de pollution. [Use of the biological model, the crayfish as a biomarker of pollution. Consequences in term of cadmium trophic transfer rates], Application a l'etude des transferts du cadmium [Knowledge-based management of European native crayfishes: Exchanges between researchers and managers], No. 367. Bulletin Francais de la Peche et de la Pisciculture. pp. 795-803. [French with English summary]

The bioaccumulation by aquatic organisms to trace metals is directly related to the exposure routes; direct contamination from the surrounding environment and trophic contamination through ingested contaminated preys. To understand disturbances to ecosystems, it is important to determine biomarkers and to quantify the respective contributions of the two exposure routes. Works presented relate to the trophic transfer of cadmium between a prey, the clam Corbicula fluminea, and one of its predators, the crayfish Astacus astacus. In order to define the uptake routes, we carried out 2 complementary approaches; the first concerning the < natural > consumption of preys contaminated during 30 days' exposure, the second consisted of directly introduction a homogenised samples of contaminated preys into the stomach of the crayfish by a force-feeding technique. Results show marked differences between natural predation of field contaminated prey and force-feeding exposure.

Simon, O. and J. Garnier-Laplace. 2004. Kinetic analysis of uranium accumulation in the bivalve Corbicula fluminea: effect of pH and direct exposure levels. Aquatic Toxicology 68(2):95-108.

The bioaccumulation of natural uranium in the freshwater bivalve Corbicula fluminea was investigated subsequent to the bivalve's experimental waterborne exposures. A first experiment determined the accumulation rate (transfer efficiency, tissular distribution) and subcellular distribution of uranium in organs after over 42 days of uranium exposure (100 μg/L; pH 7) and later following 60 days of depuration. Results showed that there was direct transfer of uranium to the bivalve organs ([U]organism/[U]water = 0.16, fresh weight, fw). The highest accumulation levels occurred in the visceral mass and remained constant throughout the exposure duration, although a linear increase in the U concentration in the gills was observed (2.98 plus or minus 1.3-10.9 plus or minus 3.7 μg /g between Days 2 and 42). A second set of experiments were performed in order to test the influence of the exposure levels (100; 500; 1500 μg /g) and pH (7 and 8.1) on the bioaccumulation capacities. A marked difference of U distribution is observed as a function of exposure levels (gills were favored in the case of high exposure levels-relative burden: 49.1 plus or minus 3% (1500 μg /g), whereas the visceral mass presented higher accumulation levels at environmentally relevant U concentrations). Uranium concentration in the insoluble fraction (80%) in the whole body does not depend upon exposure levels in the water column or upon duration. These experiments did not allow any link to be established between the free-metal ion concentration and the bioaccumulation efficiency. Results showed a significant pH effect and indicated a link between the exposure conditions and the distribution of uranium in the bivalve organs.

Simon, O., F. Ribeyre and A. Boudou. 2000. Comparative experimental study of cadmium and methylmercury trophic transfers between the asiatic clam Corbicula fluminea and the crayfish Astacus astacus. Archive of Environmental Contamination and Toxicology 38(3):317-326.

Cadmium (Cd) and methylmercury (MeHg) trophic transfers were analyzed between the Asiatic clam Corbicula fluminea and the crayfish Astacus astacus. Metal bioaccumulation in crayfish was quantified after 5, 10, and 15 days of exposure via daily ingestion of soft bodies of C. fluminea, previously exposed during 7 days to Cd (20 μg/L) and MeHg (4 μg/L). Bioaccumulation kinetics in the predator were investigated at organ and tissue levels: hemolymph, tail muscle, hepatopancreas, gills, stomach/mesenteron, intestine, green gland, carapace. Trophic transfer rates were estimated at the whole organism level. Results showed marked differences (1) in assimilation efficiencies, mean transfer rates being 5% for Cd and 16% for MeHg; and (2) in the metal distribution within the different tissue compartments of the crayfish: for Cd, the trophic uptake leads to high concentrations in the hepatopancreas and small accumulation in the muscle tissue; for MeHg, the highest levels of bioaccumulation occur in the green gland and in the tail muscle. From an ecotoxicological point of view, these experimental data suggest a small risk of Cd transfer between the crayfish and predators, humans included; on the other hand, Hg distribution in the muscle and accumulation trends in this tissue represent an obvious risk of transfer.

Sinclair, R. M. l963. Effects of an Introduced Clam (Corbicula) on Water Quality in the Tennessee River Valley. Tennessee Stream Pollution Control Board, Tennessee Department of Public Health. 14 pp.

The life history, ecology, and control of Corbicula are presented and discussed in relation to potable and industrial water supplies in Tennessee. Notes on the effects of these bivalves on the sand and gravel industry are also presented. Comparisons are made with Dreissena polymorpha.

Sinclair, R. M. l964. Clam pests in Tennessee water supplies. Journal of the American Water Works Association 56:592 599.

The life history, ecology, and control of Corbicula are presented and discussed in relation to potable and industrial water supplies in Tennessee. Notes on the effects of these bivalves on the sand and gravel industry are also presented. Comparisons are made with Dreissena polymorpha.

Sinclair, R. M. l97l. Corbicula variation and Dreissena parallels. The Biologist 53(3):l53 l59.

The biology and ecology of Corbicula fluminea and Dreissena polymorpha are compared and contrasted with respect to their penchant for biofouling. Notes on their zoogeography and systematics are also given.

Sinclair, R. M. l97l. Annotated bibliography on the exotic bivalve Corbicula in North America. l900 l97l. Sterkiana 43:ll l8.

An annotated bibliography of works on bivalves in the genus Corbicula published from l900 l97l is presented. Papers are arranged under the following subject headings: Introduction, systematics, ecology, life history and morphology, salinity and related estuarine species, North American distribution, effects on hydroinstallations and control, fisheries, water quality and effect of pollution, role in echinostomiasis, physiology, and mass mortalities.

Sinclair, R. M. l974. Effects of an introduced clam Corbicula on water quality in the Tennessee River Valley.